francisco. oh, mayor as well. yeah, that's part of the job description. yeah, mayor of san francisco. >> the city is extremely concerned about the emission of green house gasses and making san francisco a sustainable city. >> we need to find other ways to create energy without harm to the environment and this is one source. >> we have over 2 megawatts of solar on various city buildings. we are looking at tidal power and we're beginning to look at geothermal power. >> we're on the roof of the moscone center of san francisco and we have 2500 panels that power the center. >> here we are using real energy, energy from the sun, free energy from the sun coming in right here. this converts directly into electricity. >> all these technologies cost money. they '